Crosslinking agents based on amino resins and coating compositions made with these are well known in the art and have been used for more than half a century in diverse applications including general industrial coatings, automotive coatings, coil coatings, powder coatings, baking enamels, and wood finishes. These crosslinking agents are based on reaction products of formaldehyde with amine or amide compounds such as melamine, guanamines, urea, and substituted ureas. Among the major drawbacks of these amino resin based coatings are formaldehyde emissions during cure.
Various crosslinking compositions have been developed that are based on combinations of aminoplast formers and aldehydes other than formaldehyde. Many of these are either less efficient or more expensive than the known formaldehyde-based systems, or are otherwise objectionable from a safety and health view. Despite the numerous efforts made, none of the crosslinker resins proposed has found wide market acceptance.
It is therefore an object of this invention to provide crosslinking compositions that have no formaldehyde emission, or a low formaldehyde emission that can be tolerated from a safety and health viewpoint, and that have application properties that are either on par with the known formaldehyde based systems, or at least provide a favourable match to these known systems.